The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
N. M. Tchebakova - One of the best experts on this subject based on the ideXlab platform.
-
Needle, crown, stem, and root Phytomass of Pinus sylvestris stands in Russia
Forest Ecology and Management, 1996Co-Authors: Robert A. Monserud, A. A. Onuchin, N. M. TchebakovaAbstract:Abstract With growing concern about predicted global warming, increasing attention is being paid to the Phytomass (living plant mass) components of forest stands and their role in the carbon cycle. The ability to predict Phytomass components from commonly available inventory data would facilitate our understanding of the latter. We focus on Scots pine ( Pinus sylvestris L.) stands in Russia, with the objective of predicting stand Phytomass (Mg ha −1 ) for the four major stand components: needles, crown, stems, and roots. The study area includes regions in Russia where Scots pine is a stand-forming species: from European Russia (33°E) to Yakutia (130°E) in eastern Siberia. To ensure that results will be widely applicable, only variables consistently measured in forest inventories were considered as possible predictors: stand age, site quality class, and stocking (stand stem volume with bark, m 3 ha −1 ). Stand Phytomass data were obtained from numerous regional and local Phytomass studies, and supplemented with additional unpublished data. This is the first comprehensive study synthesizing stand level Phytomass relations for P. sylvestris for most of its range in Russia. The combined results from over 18 regional and local Phytomass studies provide a level of generality that is not possible with individual local studies. In addition to estimating stand Phytomass components across a wide range of conditions, these Phytomass models can also be used to verify carbon allocation rules in process-based models.
-
Change in Siberian Phytomass predicted for global warming.
Silva Fennica, 1996Co-Authors: Robert A. Monserud, N. M. Tchebakova, T.p. Kolchugina, Olga V. DenissenkoAbstract:Part I Climate ChangeAn equilibrium model driven by climatic parameters, the Siberian Vegetation Model, was used to estimate changes in the Phytomass of Siberian vegetation under climate change scenarios (CO2 doubling) from four general circulation models (GCM’s) of the atmosphere. Ecosystems were classified using a three-dimensional climatic ordination of growing degree days (above a 5 °C threshold), Budyko’s dryness index (based on radiation balance and annual precipitation), and Conrad’s continentality index. Phytomass density was estimated using published data of Bazilevich covering all vegetation zones in Siberia. Under current climate, total Phytomass of Siberia is estimated to be 74.1 ± 2.0 Pg. Note that this estimate is based on the current forested percentage in each vegetation class compiled from forest inventory data. Moderate warming associated with the GISS (Goddard Institute for Space Studies) and OSU (Oregon State Univ.) projections resulted in a 23–26% increase in Phytomass (to 91.3 ± 2.1 Pg and 93.6 ± 2.4 Pg, respectively), primarily due to an increase in the productive Southern Taiga and Subtaiga classes. Greater warming associated with the GFDL (General Fluid Dynamics Laboratory) and UKMO (United Kingdom Meteorological Office) projections resulted in a small 3–7% increase in Phytomass (to 76.6 ± 1.3 Pg and 79.6 ± 1.2 Pg, respectively). A major component of predicted changes using GFDL and UKMO is the introduction of a vast Temperate Forest-Steppe class covering nearly 40% of the area of Siberia, at the expense of Taiga; with current climate, this vegetation class is nearly non-existent in Siberia. In addition, Subboreal Forest-Steppe Phytomass doubles with all GCM predictions. In all four climate change scenarios, the predicted Phytomass stock of all colder, northern classes is reduced considerably (viz., Tundra, Forest-Tundra, Northern Taiga, and Middle Taiga). Phytomass in Subtaiga increases greatly with all scenarios, from a doubling with GFDL to quadrupling with OSU and GISS. Overall, Phytomass of the Taiga biome (Northern, Middle, Southern, and Subtaiga) increased 15% in the moderate OSU and GISS scenarios and decreased by a third in the warmer UKMO and GFDL projections. In addition, a sensitivity analysis found that the percentage of a vegetation class that is forested is a major factor determining Phytomass distribution. From 25 to 50% more Phytomass is predicted under climate change if the forested proportion corresponding to potential rather than current vegetation is assumed
-
Predicted effects of climate change on Phytomass and net primary productivity in Siberia
1995Co-Authors: R.a. Monserud, N. M. Tchebakova, T.p. KolchuginaAbstract:Under current climate, the authors estimate the total Phytomass of Siberia to be 74.1 {+-} 2.0 Pg. in all four climate change scenarios, the predicted Phytomass stock of all colder, northern classes is reduced considerably. Forest-Steppe greatly expands with all GCM`s. A notable feature of these increases is the large introduction of Temperate Forest-Steppe under climate change. Moderate warming associated with the OSU and GISS projections resulted in a 23--26% increase in Phytomass, respectively. Great warming associated with the UKMO and GFDL projections resulted in a small 3%--7% increase in Phytomass, respectively. Thus, the Siberian Phytomass component is sensitive to the degree of climate change, even though all scenarios correspond to the same CO{sub 2} doubling equilibrium.
-
Change in Phytomass and net primary productivity for Siberia from the Mid‐Holocene to the Present
Global Biogeochemical Cycles, 1995Co-Authors: Robert A. Monserud, T.p. Kolchugina, Olga V. Denissenko, N. M. TchebakovaAbstract:Phytomass (live plant mass) and net primary productivity are major components of the terrestrial carbon balance. A major location for Phytomass storage is the subcontinent of Siberia, which is dominated by extensive reaches of taiga (boreal forest). The responsiveness of the Phytomass component of the carbon pool is examined by comparing vegetation in the mid-Holocene (4600–6000 years before present) to modern potential vegetation. The mid-Holocene was warmer and moister in middle and northern Siberia than today, producing conditions ideal for boreal forest growth. As a result, both northern and middle taiga were dominated by shade-tolerant dark-needled species that thrive in moist climates. Today, shade-tolerant dark-needled taiga is restricted to western Siberia and the highlands of central Siberia, with its central and eastern components in the mid-Holocene replaced today by light-demanding light-needled species with lower productivity and Phytomass. Total Phytomass in Siberia in the mid-Holocene was 105.0 ± 3.1 Pg, compared to 85.9 ± 3.2 Pg in modern times, a loss of 19.1 ± 3.1 Pg of Phytomass. The reduction in dark-needled northern and middle taiga classes results in a loss of 28.8 Pg, while the expansion of the corresponding light-needled taiga results in a gain of 13.5 Pg, a net loss of 15.3 Pg. The loss is actually greater, because the modern figures are for potential vegetation and not adjusted for agriculture and other anthropogenic disturbances. Given long periods for vegetation to approach equilibrium with climate, the Phytomass component of the carbon pool is responsive to climate change. Changes in net primary productivity (NPP) for Siberia between the mid-Holocene and the present were not as large as changes in Phytomass. A minor decrease in NPP (0.6 Pg yr−1, 10%) has occurred under our cooler modern climate, primarily due to the shift from dark-needled taiga in the mid-Holocene to light-needled taiga today.
Robert A. Monserud - One of the best experts on this subject based on the ideXlab platform.
-
Needle, crown, stem, and root Phytomass of Pinus sylvestris stands in Russia
Forest Ecology and Management, 1996Co-Authors: Robert A. Monserud, A. A. Onuchin, N. M. TchebakovaAbstract:Abstract With growing concern about predicted global warming, increasing attention is being paid to the Phytomass (living plant mass) components of forest stands and their role in the carbon cycle. The ability to predict Phytomass components from commonly available inventory data would facilitate our understanding of the latter. We focus on Scots pine ( Pinus sylvestris L.) stands in Russia, with the objective of predicting stand Phytomass (Mg ha −1 ) for the four major stand components: needles, crown, stems, and roots. The study area includes regions in Russia where Scots pine is a stand-forming species: from European Russia (33°E) to Yakutia (130°E) in eastern Siberia. To ensure that results will be widely applicable, only variables consistently measured in forest inventories were considered as possible predictors: stand age, site quality class, and stocking (stand stem volume with bark, m 3 ha −1 ). Stand Phytomass data were obtained from numerous regional and local Phytomass studies, and supplemented with additional unpublished data. This is the first comprehensive study synthesizing stand level Phytomass relations for P. sylvestris for most of its range in Russia. The combined results from over 18 regional and local Phytomass studies provide a level of generality that is not possible with individual local studies. In addition to estimating stand Phytomass components across a wide range of conditions, these Phytomass models can also be used to verify carbon allocation rules in process-based models.
-
Change in Siberian Phytomass predicted for global warming.
Silva Fennica, 1996Co-Authors: Robert A. Monserud, N. M. Tchebakova, T.p. Kolchugina, Olga V. DenissenkoAbstract:Part I Climate ChangeAn equilibrium model driven by climatic parameters, the Siberian Vegetation Model, was used to estimate changes in the Phytomass of Siberian vegetation under climate change scenarios (CO2 doubling) from four general circulation models (GCM’s) of the atmosphere. Ecosystems were classified using a three-dimensional climatic ordination of growing degree days (above a 5 °C threshold), Budyko’s dryness index (based on radiation balance and annual precipitation), and Conrad’s continentality index. Phytomass density was estimated using published data of Bazilevich covering all vegetation zones in Siberia. Under current climate, total Phytomass of Siberia is estimated to be 74.1 ± 2.0 Pg. Note that this estimate is based on the current forested percentage in each vegetation class compiled from forest inventory data. Moderate warming associated with the GISS (Goddard Institute for Space Studies) and OSU (Oregon State Univ.) projections resulted in a 23–26% increase in Phytomass (to 91.3 ± 2.1 Pg and 93.6 ± 2.4 Pg, respectively), primarily due to an increase in the productive Southern Taiga and Subtaiga classes. Greater warming associated with the GFDL (General Fluid Dynamics Laboratory) and UKMO (United Kingdom Meteorological Office) projections resulted in a small 3–7% increase in Phytomass (to 76.6 ± 1.3 Pg and 79.6 ± 1.2 Pg, respectively). A major component of predicted changes using GFDL and UKMO is the introduction of a vast Temperate Forest-Steppe class covering nearly 40% of the area of Siberia, at the expense of Taiga; with current climate, this vegetation class is nearly non-existent in Siberia. In addition, Subboreal Forest-Steppe Phytomass doubles with all GCM predictions. In all four climate change scenarios, the predicted Phytomass stock of all colder, northern classes is reduced considerably (viz., Tundra, Forest-Tundra, Northern Taiga, and Middle Taiga). Phytomass in Subtaiga increases greatly with all scenarios, from a doubling with GFDL to quadrupling with OSU and GISS. Overall, Phytomass of the Taiga biome (Northern, Middle, Southern, and Subtaiga) increased 15% in the moderate OSU and GISS scenarios and decreased by a third in the warmer UKMO and GFDL projections. In addition, a sensitivity analysis found that the percentage of a vegetation class that is forested is a major factor determining Phytomass distribution. From 25 to 50% more Phytomass is predicted under climate change if the forested proportion corresponding to potential rather than current vegetation is assumed
-
Change in Phytomass and net primary productivity for Siberia from the Mid‐Holocene to the Present
Global Biogeochemical Cycles, 1995Co-Authors: Robert A. Monserud, T.p. Kolchugina, Olga V. Denissenko, N. M. TchebakovaAbstract:Phytomass (live plant mass) and net primary productivity are major components of the terrestrial carbon balance. A major location for Phytomass storage is the subcontinent of Siberia, which is dominated by extensive reaches of taiga (boreal forest). The responsiveness of the Phytomass component of the carbon pool is examined by comparing vegetation in the mid-Holocene (4600–6000 years before present) to modern potential vegetation. The mid-Holocene was warmer and moister in middle and northern Siberia than today, producing conditions ideal for boreal forest growth. As a result, both northern and middle taiga were dominated by shade-tolerant dark-needled species that thrive in moist climates. Today, shade-tolerant dark-needled taiga is restricted to western Siberia and the highlands of central Siberia, with its central and eastern components in the mid-Holocene replaced today by light-demanding light-needled species with lower productivity and Phytomass. Total Phytomass in Siberia in the mid-Holocene was 105.0 ± 3.1 Pg, compared to 85.9 ± 3.2 Pg in modern times, a loss of 19.1 ± 3.1 Pg of Phytomass. The reduction in dark-needled northern and middle taiga classes results in a loss of 28.8 Pg, while the expansion of the corresponding light-needled taiga results in a gain of 13.5 Pg, a net loss of 15.3 Pg. The loss is actually greater, because the modern figures are for potential vegetation and not adjusted for agriculture and other anthropogenic disturbances. Given long periods for vegetation to approach equilibrium with climate, the Phytomass component of the carbon pool is responsive to climate change. Changes in net primary productivity (NPP) for Siberia between the mid-Holocene and the present were not as large as changes in Phytomass. A minor decrease in NPP (0.6 Pg yr−1, 10%) has occurred under our cooler modern climate, primarily due to the shift from dark-needled taiga in the mid-Holocene to light-needled taiga today.
José M. Paruelo - One of the best experts on this subject based on the ideXlab platform.
-
Do Grasslands Have a Memory: Modeling Phytomass Production of a Semiarid South African Grassland
Ecosystems, 2004Co-Authors: Thorsten Wiegand, Hennie A. Snyman, Klaus Kellner, José M. ParueloAbstract:We analyzed data sets on Phytomass production, basal cover, and monthly precipitation of a semiarid grassland in South Africa for good, medium, and poor rangeland condition (a) to investigate whether Phytomass production per unit of basal cover differed among rangeland conditions, (b) to quantify the time scales of a carryover effect from production in previous months, and (c) to construct predictive models for monthly Phytomass. Finally, we applied the best models to a 73-year data set of monthly precipitation data to study the long-term variability of grassland production. Our results showed that mean Phytomass production per unit of basal cover did not vary significantly among the rangeland conditions—that is, vegetated patches in degraded grassland have approximately the same production as vegetated patches in grassland in good condition. Consequently, the stark decline in production with increasing degradation is a first-order effect of reduced basal area. Current-year precipitation accounted for 64%, 62%, and 36% of the interannual variation in Phytomass production for good, medium, and poor condition, respectively. We found that 61%, 68%, and 33%, respectively, of the unexplained variation is related to a memory index that combines mean monthly temperature and a memory of past precipitations. We found a carryover effect in production from the previous 4 years for grassland in good condition and from the previous 1 or 3S month for grassland in medium and poor condition. The memory effect amplified the response of production to changes in precipitation due to alternation of prolonged periods of dry or wet years/months at the time scale of the memory. The interannual variability in Phytomass production per unit basal cover (coefficient of variation [CV] = 0.42–0.50 for our 73-year prediction, CV = 0.57–0.71 for the 19-year data) was greater than the corresponding temporal variability in seasonal rainfall (CV = 0.29).
Anatoly Shvidenko - One of the best experts on this subject based on the ideXlab platform.
-
Database on structure of Phytomass of Russian forests
2005Co-Authors: D. G. Shchepashchenko, Anatoly Shvidenko, Ivan LakydaAbstract:Review of the modern databases for Phytomass structure of forests in Russia is provided. The database offered by the authors contains information about Phytomass structure, forest-typological and inventory characteristics of the stands. All forest-forming species and regions of the former Soviet Union are presented.
-
Dynamics of Phytomass and Net Primary Production of Russian Forests in 1961-1998: an attempt of aggregated estimation
2000Co-Authors: Anatoly Shvidenko, Sten Nilsson, Dmitry SchepaschenkoAbstract:Aggregated estimates of the dynamics of Phytomass and Net Primary Production (NPP) of Russian forests are presented for the period 1961-1998. The calculations for 1990 are based on detailed inventories, using data from the State Forest Account by ecoregions, available results of measurements and reference data on the productivity of forests which have been accumulated in Russia during the last decades. For 1990, the total amount of Phytomass in forest ecosystems is estimated to be 66450 Tg (=10^12g) dry matter, or 32862 Tg C. Of the total amount of Phytomass carbon, 78.0% of Phytomass are above ground (including 6.2% green part and 71.8% woody part) and 22.0% are presented by roots. The NPP is estimated to be 3660 Tg dry matter per year or 1708 Tg C yr^-1. 75.4% of NPP are allocated above ground, and 49.0% of total NPP are in green parts. During the period 1961-1998, it has been shown that Phytomass of forest ecosystems in Russia increased from 29.59 to 34.30 Pg (=10^15g) C, i.e. annual average accumulation of carbon in Phytomass is estimated at 127 Tg C yr^-1. NPP, calculated as smoothed average for a 5 year period, increased from 1488 Tg C yr^-1 in 1961 to 1735 Tg C yr^-1in 1998.
-
Forest Phytomass and carbon in European Russia
Biomass and Bioenergy, 1997Co-Authors: P. Lakida, Sten Nilsson, Anatoly ShvidenkoAbstract:Regression equations for basic fractions of forest Phytomass have been developed for the European-Ural part of Russia based on available experimental data and publications (preliminarily examined 962 sample plots and aggregations). 8 main forest forming species (pine, spruce, oak, birch, beech, aspen, alder, lime) which were involved into analysis cover in European Russia about 95% of total forested areas. The equations allow to evaluate the ratio between Phytomass fractions weight and growing stock by species, age and site indexes. The application of the equations to the Forest State Account data (1988) gives the total (living) Phytomass in forest ecosystems of European Russia (forested area of 166.0 Mha, growing stock of 20.28 bln m3) of 15.47 Pg drt matter (density 9.32 kg/m2). The total carbon pool was estimated 7.64 Pg C with average density 4.60 kg C/m2 in 1988. Analysis of uncertainties of data and used methods showed that the results which based on FSA data probably underestimate real values for about 5% with standard error +/- 7-8% with confidential (apriori) probability 0.8-0.9. Used this assumption unbiased estimate of total storage of Phytomass in forest vegetation were calculated for 1993 of 16.94 Pg (average density 10.36 kg/m2 ) and for C content respectively (8.37 Tg and 5.03 kg/m2 respectively). The changes of forest Phytomass in 1966-1993 were estimated of 4.73 Pg (or about 174 Tg of dry matter/year) and for C - 2.34 Pg, i.e. the European Russian forests provided during 1966-1993 net sink of carbon in forest vegetation about 87 Tg C annually.
-
Estimation of forest Phytomass for selected countries of the former European U.S.S.R.
Biomass and Bioenergy, 1996Co-Authors: P. Lakida, Sten Nilsson, Anatoly ShvidenkoAbstract:Abstract Models have been developed to estimate forest Phytomass fractions of major forest-forming species in Estonia, Latvia, Lithuania, Belarus, Ukraine, Moldova, Georgia, Armenia and Azerbaijan. In the development of these models, both specifically collected data (284 sample plots) and some selected data reported in other publications (229 sample plots) were used. The species analysed were pine, spruce, oak, beech, birch, aspen and alder; together these species cover some 92% of the total forested area and growing stock in the countries studied. The models developed include the ratio between the fractions of Phytomass weights (dry matter) and green growing stock (stemwood over bark) distributed over age and site indices. The Phytomass fractions studied are foliage, wood and bark of the stem; wood and bark of the crown branches; belowground woody Phytomass; and understory Phytomass. Based on 1988 Forest State Account data of the former U.S.S.R., the total Phytomass in forested areas (26.3 million ha with a growing stock of 3.85 billion m3) was estimated to be 2999.6 Tg (teragrams) dry matter, which gives a Phytomass density of 11.4 kg/m2. The total carbon storage was estimated at 1487 Tg, or 5.6 kg C/m2. Application of the results from the Phytomass studies to the 1966 and 1988 Forest State Account data sets results in a net annual average sink of 24.5 Tg C in the living Phytomass of the forest ecosystems in the countries under study over the period 1966–1988.
Richard T. Corlett - One of the best experts on this subject based on the ideXlab platform.
-
Energy and nutrient flow through the storage and consumption of upland Phytomass fuel
Forest Ecology and Management, 1997Co-Authors: Rongjun Chen, R.d. Hill, Richard T. CorlettAbstract:Abstract Villagers in Guangdong depend mainly on upland Phytomass for domestic purposes, while a few in Hong Kong also still collect it for cooking. They usually store harvested Phytomass for some time before consumption. On-site measurements in five households each of Hong Kong and Heshan showed than sun- or air-dried Phytomass fuel significantly increased moisture, but decreased calorific value and nutrient concentration with storage time. The consumption of phytofuel depends on seasons, cooking habits, its availability and the prices of alternative fuels. Surveys were conducted in 70 households of Heshan, Shenzhen and Hong Kong to quantify the consumption of Phytomass for fuel. On average, the Heshan households had a Phytomass consumption of 1.77 (summer) or 2.15 kg per capita per day (winter); the Shenzhen housholds 1.37 (summer) or 1.72 kg per capita per day (winter); and the Hong Kong households 1.07 (summer) or 1.42 kg per capita per day (winter). The average Heshan, Shenzhen and Hong Kong households had a phyto-energy consumption of 34,27 and 25 MJ per capita per day in summer respectively, and 41, 33 and 34 MJ per capita per day in winter respectively. There was a significant difference in consumption of Phytomass and phyto-energy between winter and summer, and among the Heshan, Shenzhen and Hong Kong households. Different types of stove have different heat efficiencies, and also alter the consumption of phyto-energy. On average, the stoves of Heshan, Shenzhen and Hong Kong households had a heat efficiency of 10.8%, 9.1% and 8.5% respectively. There was a significant difference in the heat efficiencies of stoves between any pair of Heshan, Shenzhen and Hong Kong households.